The present invention relates to a forming tool with punch according to the features in the preamble of patent claim 1.
From the state of the art it is known to produce sheet metal products by press-forming. These sheet metal components are in particular used in motor vehicle construction as structural vehicle body parts or as outer panels of a vehicle body. For these metallic materials, in particular steel materials in the form of sheet metal blanks are provided, wherein the blanks are then inserted into a press-forming tool and are formed by press-forming. For this a press-forming tool has a top die and a bottom die, wherein the top die and the bottom perform a vertical movement after which a mold cavity remains between the top die and the bottom die, which imposes a corresponding three-dimensional contour on the plate.
From the state of the art in particular the hot-forming and press-hardening technology is known in which the blank prior to heat treatment is heated above austenizing temperature, i.e., above 850° C., so that an austenization has occurred. The plate is then formed while in the hot state, because in this state it can be formed with a high degree of freedom while requiring only small forming forces. Subsequent thereto the plate is cooled fast or quenched so that the austenitic microstructure is transformed into a martensitic microstructure and thereby a significantly higher strength or hardness properties are established. A risk of delayed fracture or the occurrence of micro cracks such as in hard-cutting is thus avoided.
However, sometimes not only forming operations but also punching or cutting operations have to be performed prior to hardening because the forces required for the punching or cutting are smaller in this case and the wear of the punching or cutting tools is lower than in a hardened component.
Recesses or holes have to be introduced in particular so that screw connections can be generated or cables can be guided through. In order to generate such recesses on a component, corresponding punches are known from the state of the art. For example a combined forming and punching tool is known from DE 10 2008 034 996 B4. Hereby a corresponding hole punching operation is performed with the forming itself.
When three-dimensional, complex formed components are used or components with different wall thicknesses, inaccurate contact occurs in the mold cavity especially in the region of the punch between the top die and the bottom die and the already mostly formed plate situated there between.